The only explanation I can see, assuming it's not a batch of defective BSP129's, is a shorted component in the shunt regulator circuit, such as the mosfet or post-reg filter cap. Being a depletion mode sipmosfet, the BSP129 should absolutely be passing voltage in your conditions.

__________________www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

This is really a question for Bobken & for Peter D., but I'm sure others may wish to chime in.

I'd like to try the 'Bobken' regulator in a phono stage. It currently uses a not-to-dissimilar shunt regulator and starts with 22v and regulates it down to 15v.

Will this work ok as long as I don't overheat/overload the two main active devices, the BSP129 & the ZVN3310? I need to measure the current draw of the existing circuit & if it looks excessive for the devices, I may go to one regulator per active device per channel (2 active devices per channel, 4 +- regulators total) to keep within the device limits.

This of course also begs the question about the negative rail regulators. The ZVN3310 has a compliment, the ZVP3310. Can I create a negative rail version of this regulator by:

1. Reversing the orientation of the current source (BSP129 + current set resistor)?

2. Use the ZVP3310 instead of the ZVN3310 as the shunt device?

3. Reorient the power to the AD811 so that the negative supply pin is to the rail and the positive to ground? (of course, the orientation of the NP BG .01 NZ would stay the same with respect to the positive and negative supply pins.)

4. Reverse the orientation of the LM285-2.5v and of course, the polarized input capacitor and the NP output one (as NP BG's need to be oriented a certain way for the best sound)?

As an alternative, you may try the shunt regulator I'm using in this phono stage: The Phono Stage

You can order the board from me and any assortment of parts.

__________________www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

The reason I'm calling it "Bobken regulator" is because of specific parts being used. Since there is no P channel complement for depletion mosfet like BSP129 (that I'm aware of), one cannot built negative regulator mirroring the positive one. Of course other options are possible, but then it's not Bobken regulator.

__________________www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

I do not recall asking you about why you are calling this shunt regulator topology the “Bobken regulator”.

There does not have to be a complementary P channel for replacing the BSP129. The shunt regulator can be broken down into two key sections, both of which behave like two terminal devices. There is a current source and a shunt regulator, which behaves like a synthesized zener diode but with much better operating parameters. As long as the correct polarity is maintained for the circuit elements the current source can be moved to the negative rail with the BSP129 drain connected to the zener anode terminal and the zener cathode terminal is connected to ground thus providing a negative rail version of the regulator.

I do not recall asking you about why you are calling this shunt regulator topology the “Bobken regulator”.

Of course you didn't, but after reading your comments in the other thread, I feel a bit uneasy for not calling it your "old shunt regulator design". (Sorry, couldn't resist )

__________________www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC